Process for manufacturing brushes



March 17, 1959 w. WESSEL, JR 2,878,069

PROCESS FOR MANUFACTURING BRUSHES Filed Oct. 10, 1955 f1 5. Ba Z1 5. EbZ 15. EC

INVENTOR: UaHer \AesseA r, BY.

mums s ML United States Patent 2,878,069 PROCESS FOR BRUSHES WalterWessel, Jr., Re'rnscheid, Germany Application October 10, 1955, SerialNo. 539,630 Claims priority, application Germany October 11, 1954 12Claims. (Cl. 300-21 -The;present invention relates to a process formanufacturin g :brushes.

.Known brushes as well as processes and apparatus for manufacturing thesame have several disadvantages. Thus, it is exceedingly diflicult toprovide a brush whose tufts are carried bya relatively soft, yieldableand bendable member and at the same time are reliably secured to such amember.- With known brushes the tufts inevitably becomeloose and fallout after a relatively short period of time, and furthermore theprocesses used in manufacturing such known brushes are very costly andtime-consuming and require very special, expensive apparatu's'forinterconnecting the parts of the brush as well as for. heating elementsand properly positioning the same during the manufacture of the brush.

One of the objects of the present invention is to provide a brush wherethe tufts are securely connected to a bendable, relatively soft,tuft-carrying member in such a way that the tufts will not loosen eventhough the brush is flexed sharply and repeatedly and even though thebrush isused -with liquids for a long period of time.

Another object of the present invention is to provide a brush where thetufts are secured by forces in addition to those resulting. fromadhesion.

A" further object of the present invention is to provide a processcapable of causing the recesses which receive the tufts to expandtemporarily so that the tufts can be inserted very easily into theserecesses.

An additional object of the present invention is to provide a processand tuft-carrying member which causes the entrance ends of the recesseswhich receive the tufts to flare outwardly when the recesses expand soas to prevent scraping of adhesive from the tufts when the latter areinserted into the recesses.

Yet another object of the present invention .is to provide awashingbrush between whose tufts a liquid may pass through openings ofthe tuft-carrying member, this washing brush having its tufts secured ina very reliable manner which prevents the tufts from becoming loose evenafter repeated flexing of the brush and use of the same with liquidsover a long period of time.

Also, it is an object of the present invention to provide a processcapable of being performed in its entirety at room temperature andenabling a brush to be manufactur'ed in an exceedingly simple,inexpensive, quick manner which requires no skill to provide a brush ofvery superior characteristics and which does not in any way endanger thepersonnel with fumes or the like from chemicals used in the process.

With the above objects in view, the present invention mainly consists ofa brush wherein a resilient member is formed with recesses into which aplurality of tufts respectively extend, these tufts being resilientlyclamped by the resilient member. The brush of the invention ismanufactured according to a process which includes placing against thesurface of recesses of a resilient elastic member a swelling agent whichcauses said recesses to to their original size and the structureshown-in Fig. 1c

2,878,069 Patented Mar. 17, 9

expand while said swelling agent is in contact with the evaporationthereof, and while the recesses arein their expanded condition tufts arerespectively inserted into the same, these tufts having in the recessesa cross-section at least as great as that of said recesses when they arenot expanded. A suitable adhesive joins the tufts to the resilientmember and is located on the ends of the tufts which are inserted intothe recesses. The tuft ends which are located in the recesses may have across-section greater than that of the unexpanded recesses so that whenthe latter resume their original shape the tufts are resiliently grippedby the reslient member as Well as being secured thereto by adhesion. Theexpansion of the recesses is particularly desirable because the tuftsare then very easily inserted,'and according to the present inventionthe resilient body may be provided with annular extensions of eachrecess of a' tapered cross-section which causes the entrance ends of therecesses to flare outwardly when the recesses expand. With thisarrangement adhesive on the ends of the tufts will not be scraped fromthe same during insertion of the tufts into the recess. I The novelfeatures which are considered as characteristic for the invention areset forth in particular in the appended claims. The invention itself,however, both as to its construction and its method of operation,together with additional objects and advantages thereof, will be bestunderstood from the following description of specific embodiments whenread in connection with the accompanying drawings, in which:

Figs. la-lc are fragmentary, sectional, elevational views presentinvention;

Fig. ,4 is a sectional view taken along lines 4-4 of Fig. I

3 in the direction of the arrows;

Fig. 5 is an elevational diagrammatic view of a pair 1 of dies used inthe manufacture of the article of the present invention;

Fig. 6 is asectional view taken along lines 6-6 of Fig.- 5 in thedirection of the arrows; and

Fig. 7 is a sectional elevational view of a washing brush according tothe present invention.

Referring now to the drawings, Figs. la-lc show a resilient elasticmember 10, e. r g. of vulcanized rubber formed with a plurality ofrecesses 11 in one face thereof, these recesses 11 having the size shownin Fig. 1:: when the member 10 is unstressed. In the example shown inFigs. la -lo, an adhesive solution 12 of an adhesive dissolved in asolvent therefor, which solvent is also a swelling agent for theresilient elastic member is poured into the recesses 11, and before theswelling agentevaporates it is absorbed by the material at the faces ofthe recesses 11 and covers all parts of the 1 recesses by capillaryaction and by rising of the vapors as they evaporate. As a result therecesses 11 expand temporarily to the size shown in Fig. 1b, and theadhesive medium remains in the recesses. 11 are in their expandedcondition, a tuft 13 is placed in each of these recesses, and the endportion of the tuft which enters each recess is embedded in a body whichis caused to adhere to the member 10 by the adhesive medium remainingafter the swelling agent-solvent evapv orates. After such evaporationthe recesses 11 contract results.

of the apparatus used in the manufacture of the article ofthe While therecesses .The part 14 of each tuft 13 has a cross-sectional area atleast as great as that of the recesses 11 when the member is unstressedas shown in Fig. 1a. When the part 14 of each tuft is equal incross-sectional area to the cross-sectional area of the recesses 11 ofthe unstressed member 10, then the tufts are joined to the member 10 bythe adhesive medium, and the expansion of the recesses is of great valuebecause the tufts are very easily inserted into the recesses while theyare temporarily expanded. On the other hand, according to the presentinvention, the end portions 14 of the tufts 13 may have across-sectional area greater than that of the recesses 11 of theunstressed member 11 but smaller than that of the expanded recesses 11,and in this case the tufts are still very easily inserted into therecesses, and at the same time the tufts are connected to the member 10not only by adhesion but also by the resilient gripping action appliedby the member 10 to the tufts when the member 10 returns toward itsoriginal configuration during contraction of the expanded recesses. Therecesses may expand to a size approximately 10% greater than theiroriginal size.

According to the embodiment of the present invention illustrated inFigs. 2a2c, an elastic resilient member 15 is formed with recesses 16which have the size and configuration shown in Fig. 2a when the member15 is unstressed. It will be noted that the member 15 includes aplurality of annular projections 17 respectively forming extensions ofthe recesses 16 and having the tapered, somewhat conical cross-sectionindicated in Fig. 2a, these projections being integral with the member15. The

member 15 is immersed in a swelling agent which causes the recesses 16to swell to the size indicated in Fig. 2b, and it will be noted that thetapering of the annular projections 17 cause these annular projectionsto flare outwardly as a result of the swelling, as indicated in Fig.212. Thus the annular projections reduce the time required forexpansion. Then tufts 13 whose ends are embedded in bodies 14 are, afterbodies 14 are dipped in a suitable adhesive solution, inserted into thetemporarily expanded recesses 16, and because of the outward flaring ofthe annular projections 17, there is no danger of any of the adhesivemedium becoming scraped from the tuft during insertion thereof into therecess. These recesses then automatically contract to their originalsize due to evaporation of the swelling agent, and the structure thenappears as shown in Fig. 2c. As was the case with the embodiment ofFigs. la-lc, with the embodiment of Figs. 2a-2c the end 14 of the tufthas a size in cross-section at least as great as the cross-section ofeach recess 16 of the unstressed member 15, so that when thecross-section of part 14 of each tuft is equal to the cross-section ofeach recess 16 the tufts are connected to the member 15 by the adhesiveand when the cross-section of part 14 is greater than that of eachrecess 16 the tufts are connected to the r member 15 by the adhesive andby being resiliently gripped by member 15.

Each of the tufts of the present invention is formed from a group offairly long hairs which preferably are fairly soft, and this group ofhairs is inserted at one end into a solution of a suitable plasticadhesive agent such as rubber, as will be described below, so that therubber starts to dry on the end portions of the group of hairs afterthey are withdrawn from this solution. At this time the hairs,particularly at the parts which have been inserted in the solution, arespread apart from each other undesirably. Therefore, while the plasticmaterial on the ends of the hairs of each group has not yet hardened, itis placed between a pair of dies 2!) and 21 shown in Figs. 5 and 6, thebottom die 20 being fixed to the table of a suitable press while the topdie 21 is connected to a known mechanism actuated by the operator formoving the top die 21 down to the bottom die 20. When these dies engageeach other the channels 22 and 23 thereof cooperate to form acylindrical space, and the end portions of the,

4 i hairs which were previously inserted in the plastic solution arepressed between the dies so that the plastic material which has not yethardened, so that it is still deformable, becomes shaped by the dies 20and 21 into a cylindrical body having a predetermined cross-sectionwhich, as was pointed out above, is at least as great as thecross-section of recesses 11 or 16 and may in fact be preferablyslightly greater than this latter cross-section. Moreover, the pressingof the tufts in this way between the dies 20 and 21 forms the plastic onthe ends of the hairs of each tuft into a dense mass in which the hairsof each tuft are embedded.

Figs. 3 and 4 show a device used in the manufacture of the brush of theinvention. This device includes a pair of spaced parallel side walls 25interconnected by a third wall 26 so as to form a member ofsubstantially U-shaped cross-section. The side walls 25 are formed withelongated cutouts extending from their free edges up to the wall 26 withthe elongated cutouts 27 of one wall 25 aligned with those of the otherwall 25. A'row of tufts 13 is placed next to the wall 26 in a positionextending through the free space between the wall '25 and through thecutouts therein and beyond the walls 25, as indicated in Fig. 4. Then astrip 28 of a predetermined thickness is placed between the walls 25against this row of tufts and a second row of tufts are placed in aposition extending through the pairs of aligned cutouts 27 and locatedagainst the strip 28, as is indicated in Fig. 4, and then a second strip28 is placed against the second row of tufts. This is repeated until aplurality of rows of tufts are carried by the structure in the mannerindicated in Figs. 3 and 4. Elastic bands 29 are then placed around thefree ends of the wall 26 and the strips 28 in the manner indicated inFig. 3 in order to hold the tufts in position. With this structure allof the tends 14 of the tufts may be simultaneously inserted into asolution of a suitable adhesive medium, and the spaces between thecutouts 27 and the thickness of the strips 28 is such that there is nodanger of a pair of tufts sticking to each other. After the adhesive isthus placed on the ends 14 of the tufts, the latter, after removal fromthe devices of Figs. 3 and 4, may be inserted into the recesses 11 or16.

Fig. 7 shows the structure of the invention incorporated into a washingbrush according to the inventron. tially rectangular configuration, andas is indicated in Fig. 7 the structure of Fig. 2 is shown forming partof the washing brush of the invention, this structure of Fig. 2 beingmodified only in that the member 15' is formed between the recesses 16with bores 30 through which washliquid may flow. The member 15 is joinedwith a suitable adhesive to an elastic, resilient, bendable member 31 inthe manner indicated in Fig. 7, this member 31 defining with the member15' a free space 32 which communicates with the bores 30 and with a bore33 v formed in member 31. Any suitable fitting is fixedto the member 31and communicates with bore 33 for connecting the brush to a source ofwater or the like which may flow through the bore 33 into the chamber 32and from the latter through the bores 30.

The structure of Fig. 7 forms a particularly fine Washing brush forseveral reasons. In the first-place the member 31 as well as member 15'are both easily bendable and made of an elastic relatively soft materialwhich will not scratch a painted surface or the like.

plicated shapes in order to provide a particularly good cleaning action.Furthermore, a brush of this type because it is used with liquid andbecause it is bent in different ways frequently is subject to greatstresses which would cause conventional brushes to deteriorate rapidly.-However, with the present invention the brush of Fig. 7 is assured of along life for the following reasons:

When the brush is bent so that the top face assumes This brushpreferably has an elongated substan-' Because. of their bendability, thebrush can easily conform to coma concave curvature and the bottom faceof .member 15' assumes a convex curvature, there is a tendency for therecesses in which the tufts are located to expand at their outer endsand eventually cause the tufts to become loose and fall out. This doesnot happen with the present invention because of the annular projections17 which remain in engagement with the tufts even if the brush is bentin this manner. If these projections 17 were not present and therecesses terminated flush with the outer face of member 15', there wouldindeed be a tendency for the tufts to become loose after a certainperiod of time and use of the brush, particularly if the tufts are notresiliently gripped and are held only by adhesion. Furthermore, wherethe end portions of the tufts which are located in the recesses have across-section greater than that of the recesses when the member 15' isunstressed, the member 15' resiliently grips the tufts so that they areheld in place by this gripping action in addition to the adhesion, andfor this reason also with the brush of the invention, in spite of sharpbending and contact over a longer period of time with washing liquids,the brush of the invention will not deteriorate' and the tufts willremain securely joined to the brush. Thus, it will be seen that theinvention is of particular significance with a washing brush asindicated in Fig. 7.

As was pointed out above, the device of Figs. 3 and 4 is used tosimultaneously dip a plurality of tufts in an ad-' hesive solutionbefore they are inserted into the recesses. Such dipping is essentialwhen only a swelling agent is applied to the recesses of the embodimentsshown in Figs. la-lc and 2a-2c. However where, as was descirbed inconnection with Figs. la-lc, the swelling agent is also a solvent forthe adhesive agent and the adhesive agent solution is in the recesses,the dipping of the tufts in a separate adhesive medium may be omitted.It is pointed out that the embodiment of Figs. la-lc may be immersed ina swelling agent, as was described in connection with Figs. 2a 2c, andthe latter embodiment may have a swelling agent alone or a swellingagent in solution with an adhesive medium poured into its reces'ses, aswas described above in connection with Figs. la-lc. Of course, if only aswelling agent is poured into the recesses to expand the sametemporarily, then the tufts must be dipped in an adhesive solutionbefore being inserted into the recesses. The recesses remain expandedfor a period of time (3-5 minutes, e. g.) suf-' ficient to enable allthe tufts to be respectively placed therein.

The mechanical aspects of the invention have been described above. Thefollowing is an elaboration of the somewhat chemical aspects of theinvention to facilitate a better understanding thereof.

The resilient elastic material of which the body formed with therecesses is made and into which recesses the tufts are inserted may beof any natural or synthetic material which is easily bendable, resilientand at least some what elastic, and mainly which has the property ofbeing swelled by a liquid swelling agent, which does not dissolve thematerial but only causes it to swell when in contact therewith, andwhich material further returns to its original dimensions upon removalof the liquid swelling agent, e. g. by evaporation thereof. Among thesuitable materials of which the resilient member formed with recessesmay be made are vulcanized natural rubbers and synthetic rubbers such aspolychloroprene, butadiene rubbers including butadiene-acrylonitrilerubbers, butadiene-styrene rubbers, and the like, polysulfide rubbers,

polyisobutylene rubbers, and the like, as well as materialsmade from amixture of such rubbers. Vulcanized rubber is used rather than raw orunvulcanized rubber because the latter is dissolved by liquids which maybe used as swelling agents, e. g. trichlorethylene, whereas according tothe present invention it is onlydesired .that the body formed with therecesses swell by the action of the swelling agent liquid in order toincrease the size of the recesses, temporarily until the swelling agentis removed e. g. by evaporation.

In addition to vulcanized natural rubber and synthetic rubbers theresilient member formed with recesses into which the tufts areintroduced according to the present invention may be made of resilienthigh molecular weight synthetic resins such as polyvinylchloride,polyvinylidene chloride, copolymers of vinyl chloride with othermonomers such as vinyl acetate and the like, polyvinyl alcohols,polyesters, polyamides, etc.

Liquids which have the effect of swelling the abovementioned materialsare well known. A particular liquid may be suitable as a swelling forone material and not for another material. This is also well known, andthe particular liquid for any particular material is also well known andmay be determined from known compendiums hydrocarbons such as benzene,naphthalene, turpentine and the like, vegetable oils, ether, carbondisulfide, trichloroethylene, and the like. Many of these same liquidsmay be used as swelling agents for the different synthetic rubbers suchas polychloroprene, and the butadiene rubbers, as well as swellingagents such as toluol, xylol, ketones, chlorinated hydrocarbon such ascarbon tetrachloride, etc. It is preferred according to the presentinvention to utilize as a swelling agent a liquid which can be removedby evaporation at room temperature, this having the advantage ofreducing noxious fumes and also reducing the costs of apparatus whichwould be necessary if heating to high temperatures were required. Theswelling agents may be evaporated after they have achieved the desireddegree of swelling and the tufts have been inserted not only at roomtemperature but at higher temperatures also. The only criterion is thatthe temperature should not be so high as to deleteriously affect theresilient body and/or the tufts.

Any suitable adhesive agent may be utilized according to the presentinvention, the adhesive agent generally being a low molecular weightrubber or artificial plastic dissolved in a suitable solvent. Asindicated above, according to a preferred embodiment of the presentinvention the solvent for the adhesive should preferably be a swellingagent for the resilient body formed with the recesses. For example theadhesive agent may be raw rubber dissolved in trichloroethylene orbenzene, which in addition to being solvents for raw rubber also havethe elfect of swelling vulcanized rubber. Similarly, in the case ofartificial plastics, where the resilient body is for example made of ahigh molecular weight plastic such as polyvinylchloride having amolecular weight of about 4000, e. g., Geon 121, the adhesive agent maybe a solution of low molecular weight polyvinylchloride dissolved inacetone, e. g. Vinylite VYHH dissolved in acetone.

The walls forming the recesses of the resilient body are contacted withthe swelling agent, e. g. by immersion of the body in the swelling agentliquid for a suificient time to permit the recesses to enlargesufiiciently to enable the tufts to be inserted into the temporarilyenlarged recesses, e. g. for about 5 to 10 minutes.

As indicated above, it is preferred to embed the ends of the tufts in amaterial before insertion of the tufts into the recesses. This materialmay be of the same composition as the recessed member which carriesthetufts or, it may be somewhat different, e. g. raw rubber while therecessed member is vulcanized rubber.

The tuft ends may be embedded in the material preferably after the tuftends have been shaped cylindrically by the dies of Figs. 5 and 6 andplaced inthe device of Figs. 3 and 4 by immersing the tuft ends in anadhesive solution which upon evaporation of the solvents of the as'rspeoadhesive leaves a solid material in which the tuft ends are embedded.The adhesive solution may for example be natural raw rubber dissolved intrichloroethylene. It has been found advantageous according to thepresent invention to add a small amount of polyurethane, e. g. 46% tothe adhesive solution.

As also indicated above, the adhesive solution may be poured into therecesses, the solvent of the solution acting as swelling agent, inaddition to the solution acting as an adhesive for the tuft endsinserted into the recesses after the recesses have become enlarged bythe swelling agent. Upon evaporation of the solvent the recessescontract to their normal size and the adhesive holds the tufts to thewalls of the body. It is also possible to utilize as adhesive agent aself-vulcanizing adhesive solution which may contain for exampletriphenyhnethanetriisocyanate in solution in addition to the rubber.

The tufts may be of any suitable material for example badger hair, camelhair, and the like.

Although it is believed that the present invention has been adequatelydescribed above, the following example is given to further illustratethe method of the invention, the scope of the invention not howeverbeing limited to the specific details of the example.

Example A series of tufts are immersed at one end portion of each in asolution consisting of 15% raw natural rubber and 5% polyurethanedissolved in trichloroethylene. The tufts are then removed from thesolution and the material on the tufts is allowed to solidify andharden. Before hardening is completed the end portions of the tufts withthe partially hardened material thereon are placed between the diesdescribed above in connection with Figs. 5 and 6 to form at the ends ofthe tufts dense cylindrical bodies in which the hairs of the tufts areembedded.

In the meantime, a body formed with recesses and made of vulcanizedrubber is immersed in trichloroethylene for about 5 minutes or until therecesses have enlarged by about 10%. It should be noted that theoriginal diameter of the recesses was somewhat smaller than the diameterof the tuft ends prepared above, though in enlarged state the recessesare larger.

The tuft ends prepared above are inserted, after the material thereonhas substantially hardened, into the same solution as above to providethe ends with an adhesive coating and then the ends are introduced intothe enlarged recesses. The trichloroethylene is then evaporated bysimply allowing the body to stand in open air at room temperature thuscausing the recesses to contract to their original dimensions and thebrush is thus formed with the tufts securely embedded in the resilientmember.

It will be understood that each of the elements described above, or twoor more together, may also find a useful application in other types ofbrush and apparatus and process for making the same diifering from thetypes described above.

While the invention has been illustrated and described as embodied inwashing brush and apparatus and process for making the same, it is notintended to be limited to the details shown, since various modificationsand structural changes may be made without departing in any way from thespirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

v l. A process for manufacturing a brush comprising the steps ofapplying to the faces of recesses of a resilient elastic rubber member aswelling agent which causes said recesses to expand temporarily to agiven size, said recesses contracting to their original size when saidswelling agent evaporates; and respectively placing in said recesseswhile they are in their expanded condition a plurality of tufts whichhave in said recesses cross-sectional areas greater than that of thecross-sectional area of said recesses when they have their originalsize, so that when said recesses contract said tufts will be gripped bysaid rubber member.

2. A process for manufacturing a brush comprising thesteps of applyingto the faces of recesses of a resilient elastic member a swelling agentwhich causes said recesses to expand temporarily to a given size, saidrecesses contracting to their original size when said swelling agentevaporates; and respectively placing in said recesses while they are in,their expanded condition a plurality of bodies in which end portions ofa plurality of tufts are respectively embedded and which havecross-sectional areas at least as great as said recesses when saidmember is unstressed, with a medium between said bodies and member forcausing said bodies to adhere to said resilient member.

3. A process for manufacturing a brush, comprising the steps of placingin recesses of a resilient rubber member a solvent which causes saidbody to swell so that said recesses expand temporarily and thencontract; and placing in said recesses while they are expanded aplurality of tufts which respectively fill said recesses in theircontracted condition, so that when said recesses contract said tuftswill be gripped by said resilient rubber member.

4. A process for manufacturing a brush comprising the steps of dipping arubber member formed with recesses with said recesses thereof into arubber swelling agent for a length of time sufficient to cause saidrecesses to expand when said rubber member swells; and inserting aplurality of tufts which respectively fill said recesses in theiroriginal size into said recesses while they are expanded, so that whensaid recesses contract to their original size said rubber member willgrip said tufts.

5. A process for manufacturing a brush comprising the steps of dipping arubber member form with recesses with said recesses thereof into asolution of trichloroethylene for from five to ten minutes at roomtemperature to cause said recesses to expand when said rubber memberswells; and inserting a plurality of tufts which respectively fill saidrecesses in their original size into said recesses while they areexpanded, so that when said recesses contract to their original sizesaid rubber member will grip said tufts.

6. A process for manufacturing a brush, comprising the steps of placingin recesses of a resilient rubber member a rubber adhesive solutioncontaining a swelling agent which causes said member to swell so thatsaid recesses expand temporarily and then contract; and placing in saidrecesses while they are expanded a plurality of tufts which respectivelyfill said recesses in their contracted condition, so that when saidrecesses contract said tufts will be gripped by said resilient rubbermember.

7. A process for manufacturing a brush, comprising the steps of placingin recesses of a resilient rubber member a rubber adhesive solutioncontaining a swelling agent which causes said member to swell so thatsaid recesses expand temporarily and then contract; and placing in saidrecesses while they are expanded a plurality of rubber bodies which fillsaid recesses in their contracted condition and in which end portions ofa plurality of tufts are respectively embedded so that said rubberbodies adhere to said resilient member and so that the latterresiliently grips said tufts when said recesses contract to theiroriginal size. 7

8. A process for manufacturing a brush comprising the steps of dipping arubber member formed with recesses with said recesses thereof into arubber swelling agent for a length of time sufiicient to cause saidrecesses to expand when said rubber member swells; dipping a pluralityof rubber bodies in which end portions of a pin rality of tufts arerespectively embedded in a rubber adhesive solution, said rubber bodieshaving a size at least equal to that of said recesses when the latterare at their original size; and then inserting the thus dipped rubberbodies respectively into the expanded recesses so that said bodiesadhere to said member and so that the latter resiliently grips saidtufts when said recesses contract to their original size.

9. A process for manufacturing a brush comprising the steps of applyinga swelling agent to the faces of recesses of a resilient rubber memberwhich is provided with annular projections of tapered cross-sectionwhich respectively form extensions of said recesses so that saidrecesses expand and said annular projections flare outwardly; dipping aplurality of rubber bodies having a size corresponding at least to thatof the unexpanded recesses and having end portions of tufts respectivelyembedded therein into a solution of rubber adhesive; then inserting saidrubber bodies respectively into said recesses, said flared projectionspreventing the adhesive from being removed from said rubber bodiesduring insertion of the same into said recesses, whereby when saidrecesses contract to their original size said rubber bodies will adhereto said resilient member and the latter will grip said tufts.

10. A method of manufacturing a brush, comprising the steps of placingthe faces defining recesses of predetermined cross-section of aresilient body formed of a material adapted to be swelled by a liquidagent in contact with a liquid swelling agent for said material so as toincrease the cross-section of said recesses; introducing into saidrecesses with said increased cross-section tuft ends having a smallercross-section than said increased cross-section of said recesses and alarger cross-section than said predetermined cross-section; and removingsaid liquid swelling agent from said faces defining said recesses,thereby causing said recesses to contract to said predeterminedcross-section and thus to securely hold said tufts in said recesses.

11. A method of manufacturing a brush, comprising the steps of placingthe faces defining recesses of predetermined cross-section of aresilient body formed of a material adapted to be swelled by a liquidagent in contact with a liquid swelling agent for said material so as toincrease the cross-section of said recesses; introducing into saidrecesses with said increased cross-section tuft ends and an adhesiveagent adapted to be activated, said tuft ends having a smallercross-section than said increased cross-section of said recesses and alarger crosssection than said predetermined cross-section; and removingsaid liquid swelling agent from said faces defining said recesses andactivating said adhesive agent, thereby causing said recesses tocontract to said predetermined cross-section and thus to securely holdsaid tufts in said recesses.

12. A method of manufacturing a brush, comprising the steps of placingthe faces defining recesses of predetermined cross-section of aresilient body formed of a material adapted to be swelled by a liquidagent in contact with a vaporizable liquid swelling agent for saidmaterial so as to increase the cross-section of said recesses;introducing into said recesses with said increased cross-section tuftends having a smaller cross-section than said increased cross-section ofsaid recesses and a larger cross-section than said predeterminedcrosssection; and evaporating said liquid swelling agent from said facesdefining said recesses, thereby causing said recesses to contract tosaid predetermined cross-section and thus to securely hold said tufts insaid recesses.

References Cited in the file of this patent UNITED STATES PATENTS1,319,104 Morrison Oct. 21, 1919 1,413,211 Albright Apr. 18, 19221,819,070 Bohrman Aug. 18, 1931 FOREIGN PATENTS 647,642 France Nov. 27,1928

